Heating medium injectors and injection methods for heating foodstuffs

ABSTRACT

A heating medium injector includes an injector structure defining a heating medium flow path and a product flow path. The heating medium flow path extends to a contact location along an axis of the injector, while the product flow path also extends to the contact location along the injector axis. The contact location comprises a location at which the heating medium flow path and product flow path merge within the injector. In a region along the injector axis, the product flow path is defined between a first flow surface and a second flow surface. The first flow surface comprises a surface of a boundary wall separating the heating medium flow path from the product flow path and the second flow surface comprises a surface of an opposing second boundary wall. The second flow surface is in substantial thermal communication with a second flow surface cooling structure.

CROSS-REFERENCE TO RELATED APPLICATION

Applicant claims the benefit, under 35 U.S.C. § 119(e), of U.S.Provisional Patent Application No. 62/808,778 filed Feb. 21, 2019, andentitled “Direct Heating Medium Injector and Injection System andMethod.” The entire content of this provisional application isincorporated herein by this reference.

TECHNICAL FIELD OF THE INVENTION

The invention relates to apparatus and methods for neutralizingpathogens in materials, particularly foodstuffs, by direct injection ofa heating medium.

BACKGROUND OF THE INVENTION

Heat treatment is used in the food processing industry to eliminatepathogens and for other purposes. For example, milk may be heated toabout 145° F. for about thirty minutes, or to about 162° F. for aboutfifteen seconds to destroy or deactivate disease-causing microorganismsfound in milk. These heat treatment processes are commonly referred toas pasteurization. Milk or cream may also be treated by heating to 280°F. to 302° F. for two or six seconds (or more) in a process referred toas ultra-high-temperature (“UHT”) pasteurization. Pasteurization and UHTpasteurization may not entirely sterilize the product being treated, butmay be effective for killing or deactivating pathogens present in theproduct.

Heat treatment of liquid or otherwise pumpable materials like milk andcream may be indirect or direct. In indirect heat treatment systems, theheating medium remains separate from the foodstuff and heat istransferred to the foodstuff in a heat exchange device such as a tube inshell or plate-type heat exchanger. In contrast to indirect heattreatment systems, direct heat treatment systems bring the foodstuffinto direct contact with a suitable heating medium such as steam.Although this direct contact with steam adds water to the foodstuffbeing treated, that added water may be separated from the treatedfoodstuff as desired.

Direct steam heat treatment systems can be divided generally into steaminfusion systems and steam injection systems. In steam infusion systems,steam is directed through a steam inlet into a suitable steam chamberand the product to be treated is directed into the steam chamber througha separate product inlet, commonly a diffuser plate including a numberof passages through which relatively fine streams of product may flowinto the steam chamber. U.S. Pat. No. 4,591,463 describes examples ofsteam diffusion systems. In steam injection systems, a steam injector isused to inject steam into a stream of foodstuff flowing through aconduit to rapidly increase the temperature of the foodstuff to adesired treatment temperature. The added steam and product may then beheld at an elevated temperature for a desired time by causing themixture to flow through a hold tube. U.S. Pat. No. 2,022,420 provides anexample of a steam injection system.

In both steam infusion and steam injection systems, the water added tothe product during treatment may be removed from the product by applyinga vacuum sufficient to vaporize the added water, and then drawing offthe water vapor. This vaporization of added water also has the effect ofrapidly decreasing the temperature of the now heat-treated product. Inthe case of steam infusion systems, the water and heated product areremoved from the steam chamber and then directed to a vacuum chamber forapplying the desired vacuum. In the case of steam injection systems, themixture of heated product and added water is directed from the hold tubeinto a vacuum chamber where the added water is vaporized and may bedrawn off along with any remaining steam.

Although direct steam injection systems are commonly used for heattreating foodstuffs such as milk and juices, problems remain whichincrease the cost of operating such systems. Perhaps the most persistentproblem encountered in direct steam injection systems is the depositionof materials from the product, milk proteins in the case of milktreatment for example, on surfaces within the steam injector anddownstream from the steam injector. Among other things, these depositscan reduce flow through the system and must be removed periodically toallow proper operation. This removal of deposits necessitates shuttingdown the treatment system and these shut downs increase operation costsand reduce productivity. In applications beyond dairy products,deposition may be so rapid that passages carrying the product to betreated become completely plugged in a very short period of time, a fewseconds or a few minutes. The deposition problem thus prevents priordirect steam injection systems from being used for heat treating certainproducts, such as products including meat or egg proteins, especiallyraw (that is, uncooked) meat proteins in fibrous and other forms.

The problem of product deposition on surfaces of a direct steam injectoris exacerbated by the configuration of product flow passages which areintended to facilitate quick and even heating of the product. Inparticular, direct steam injectors may be configured to produce a narrowstream of product to bring into contact with steam in the injector. Inorder to produce such a thin stream of product, a direct steam injectormay cause the product to flow through a narrow flow passage,particularly a narrow annular flow passage, and steam may be broughtinto contact with the thin stream of product exiting the narrow flowpassage. U.S. Pat. No. 3,988,112 shows an example of a steam injector inwhich the product to be treated is forced through a narrow annular flowpath and steam is applied to the thin stream of product exiting theannular flow path. Although these injector configurations may beeffective for allowing the product to be quickly brought to the desiredtreatment temperature, the narrow structures through which the productmust flow are susceptible to rapid deposition of constituents from theproduct and are subject to plugging from deposited materials. Thestructure shown in U.S. Pat. No. 3,988,112 attempts to address theproblem of product deposition on the injector surfaces downstream of theinjection point by releasing a cold liquid along the surfaces containingthe heated mixture. This patent also shows cooling surfaces of theinjector downstream from the injection point by circulating a coolantthrough chambers formed in the walls of the injector downstream from thepoint where steam is injected into the product. While the surfacewashing and surface cooling in the injector downstream from theinjection point may be effective to increase run times for someproducts, the techniques shown in U.S. Pat. No. 3,988,112 do noteliminate product deposition and may be entirely ineffective for sometypes of products. Also, the surface washing shown in U.S. Pat. No.3,988,112 may lead to uneven heating in the product to be treated andmay reduce the effectiveness of the heat treatment with regard toeliminating pathogens.

U.S. Patent Application Publication No. 2016/0143343 discloses a directsteam injector in which surfaces within the injector which come incontact with heated product such as milk are formed from polyether etherketone, commonly referred to as PEEK, in an effort to reduce thetendency for product deposits to form on surfaces of the injector. PEEKis used in this prior injector not only for reducing the tendency forthe formation of deposits and burning in the injector, but also for itsresistance to cleaning agents and ability to withstand the temperaturesencountered in the injector. However, the use of PEEK within theinjector disclosed in U.S. Patent Application Publication No.2016/0143343 does not eliminate product deposition and thus theinjection system disclosed in this publication relies on a sensorarrangement which can be used to adjust flow paths within the injectorto help ensure the desired level of heating in the product as depositsform on the injector surfaces.

SUMMARY OF THE INVENTION

It is an object of the invention to provide direct heating mediuminjectors and direct heating medium injection methods which overcome theproblem of undue deposition of product constituents on surfaces withinthe injector. In particular, it is an object of the present invention toprovide direct heating medium injectors and direct heating mediuminjection methods which reduce or eliminate deposits of productconstituents on surfaces within the injector to thereby increase runtime for products such as milk and to allow heat treatment of productsincluding meat or egg proteins for example, especially raw meat or eggproteins, that could not previously be treated by direct steam injectiondue to high deposition rates and plugging.

According to various aspects of the present invention described indetail below, some of the surfaces within the injector that come incontact with the product to be treated are cooled by a suitable coolingarrangement to at least reduce the rate at which product constituentsform deposits on those surfaces. In particular, certain surfaces withinthe injector upstream of the steam injection point are cooled by asuitable cooling arrangement. It has been determined that cooling someof these surfaces prevents undue deposition of product constituents onthose surfaces, and surprisingly, prevents undue deposition of productconstituents on adjacent or nearby surfaces within the injector whichare not cooled and are formed from standard injector materials such asstainless steel. Other surfaces in an injector in accordance with thepresent invention may be formed from a temperature moderating material.As used in this disclosure and the accompanying claims, a “temperaturemoderating material” (sometimes referred to herein as “TMOD material”)comprises a material having a specific heat of no less thanapproximately 750 J/kg K, and preferably no less than approximately 900J/kg K, and, more preferably, no less than approximately 1000 J/kg K. Aclass of materials particularly suited for use as a TMOD material inaccordance with the present invention comprises plastics which have aspecific heat of no less than approximately 1000 J/kg K and are suitablefor providing food contact surfaces, retain structural integrity,maintain dimensional stability, and do not degrade at temperatures whichmay be encountered in a heating medium injection system (which may be350° F. or somewhat higher in some applications). Specific examples ofsuitable TMOD materials will be described below in connection with theillustrated embodiments.

A heating medium injector according to a first aspect of the presentinvention includes an injector structure, a heating medium flow pathdefined within the injector structure, and a product flow path definedwithin the injector structure. The heating medium flow path extends froma heating medium inlet opening to a contact location along an axis ofthe injector, while the product flow path extends from a product inletopening to the contact location. The contact location comprises alocation at a coordinate along the injector axis at which the heatingmedium flow path and product flow path merge within the injectorstructure, that is, first come together along the direction of flowthrough the injector, to allow mixing of the heating medium and product.In a first region along the injector axis, the product flow path isdefined between a first flow surface and a second flow surface. Thefirst flow surface comprises a surface of a first boundary wallseparating the heating medium flow path from the product flow path inthe first region and the second flow surface comprises a surface of asecond boundary wall located opposite to the first flow surface acrossthe product flow path. According to this first aspect of the invention,the second flow surface is in substantial thermal communication with asecond flow surface cooling structure. This second flow surface coolingstructure is either formed within or connected to the second boundarywall and is isolated from the product flow path.

The present invention also encompasses methods for injecting a heatingmedium into liquids or other pumpable materials. Methods according tothis second aspect of the invention include directing a heating mediumin a heating medium flow path and directing a product to be treated in aproduct flow path, both from a respective inlet location and along aninjector axis to a contact location along the injector axis. The productflow path in a first region along the injector axis is defined between afirst flow surface and a second flow surface as described above inconnection with a heating medium injector according to the first aspectof the invention. Methods embodying this second aspect of the inventionalso include cooling at least some of the second flow surface through asecond flow surface cooling structure isolated from the product flowpath. This cooling is performed while the heating medium is directedlong the heating medium flow path and the product is directed along theproduct flow path.

Cooling the second flow surface of the product flow path through theinjector structure at least reduces the rate at which constituents fromthe product form deposits on the surfaces which define the product flowpath. In the case of some products to be treated, the deposition ofconstituents from the product being treated may be eliminated entirely.This reduction of deposits from constituents in the product beingtreated allows the injector to operate for longer periods beforecleaning is required or desirable. The use of cooling for the productflow path second surface, that is, the surface opposite to the wallwhich separates the product flow path from the heating medium flow path,may also allow an injector according to the invention to be used forheat treating products which could not previously be heat treated. Suchproducts encompass products which include raw meat or egg proteins, thatis, proteins which have not been denatured by cooking, and particularlyraw fibrous meat or egg proteins. Direct heating medium injectors andheating medium injection methods according to the present invention maythus be used, for example, to pasteurize materials including raw meatproteins and egg proteins which remain undenatured in the course ofpasteurization. As used herein, “meat protein” includes proteins derivedfrom the meat of any animal including, mammals, fish and other seafoods,and birds. As used herein, “egg protein” includes proteins derived fromchicken and similar eggs. Beyond the application to the pasteurizationof raw meat proteins and egg proteins, aspects of the present inventionhave application in heat treating many types of products for manypurposes.

Where a surface of a given flow path is in substantial thermalcommunication with a cooling structure to reduce or eliminate depositionof product constituents along the flow path, the cooling structureemployed may comprise any suitable arrangement which is capable ofremoving heat from the surface so as to reduce the temperature of thesurface to the desired operating temperature. Suitable coolingstructures include coolant circulating chambers through which a suitablecoolant fluid may be circulated. Alternatively, thermoelectric deviceslocated along the wall defining the respective surface to be cooled maybe used to effect the desired cooling in some cases. Forced air andother cooling arrangements may also be employed as cooling structuresaccording to the present invention as will be discussed further below inconnection with the example embodiments. In the case of any coolingstructure in accordance with the present invention, the coolingstructure is isolated from flow paths within the injector so that thereis no mass transfer from the cooling structure to the flow paths. Forexample, in the case of coolant circulating chambers, the chambers arenot in fluid communication with the flow paths which would allow thecoolant material to make direct contact with and mix with the materialsin the product flow path.

As used in this description of the invention and the following claims,in “substantial thermal communication” with a surface of a flow pathmeans in thermal contact with the surface across one or more heatconductive materials so as to facilitate the transfer of heat in adirection from the surface away from the flow path across the one ormore heat conductive materials to effect reasonable control of thetemperature of the surface. For example, a cooling structure such as acoolant circulating chamber separated from a given surface by a wall ofmaterial 0.25 inches thick or less having a thermal conductivity of 10W/m K would be in substantial thermal communication with the givensurface. A thicker wall at this thermal conductivity could still providesubstantial thermal communication within the scope of the presentinvention, albeit with reduced capability of providing the desiredtemperature control. Additional examples of structures in substantialthermal communication with a given surface will be described below inconnection with the illustrated embodiments.

Where a TMOD material is used for a given surface, the surface is formedin the TMOD material. As used in this description and the followingclaims, “formed in” a given material or given materials means that thesurface is either molded, machined, extruded, or similarly formed in orfrom a mass of the material, or formed by an additive manufacturingtechnique such as 3D printing, either with or without polishing or othertreatment to achieve a desired surface smoothness.

In some implementations of an injector according to the first aspect ofthe invention, portions of the product flow path may be formed from TMODmaterial. For example, an injector structure according to the presentinvention may be made up of several separately formed components whichconnect together to form the product flow path and heating medium flowpath. In these implementations, some of the components may be formedfrom one or more TMOD materials while others are formed from othermaterials and rely on cooling structures to provide cooling of productflow surfaces according to the present invention, or include no coolingstructures. One particular embodiment includes a component formed from aTMOD material which defines the product inlet opening and a portion ofthe product flow path adjacent to the product inlet opening. Thisportion of the product flow path may be arcuate in shape defining anelbow which brings the product flow path into alignment with theinjector axis.

In some implementations of an injector according to the first aspect ofthe invention, both the heating medium flow path and the product flowpath in the first region comprise a respective annular flow path. Thetwo annular flow paths may be concentrically arranged, preferably aboutthe injector axis. In this concentric annular flow arrangement, theannular flow area of the heating medium flow path may be located on theinside with respect to the annular flow area of the product flow path orvice versa. In either case the first boundary wall between the heatingmedium annular flow path and the product annular flow path comprises anannular wall.

Particularly in implementations in which the heating medium flow path inthe first region comprises an annular shape, the heating medium flowpath may include a frustoconically shaped section adjacent to thecontact location. This frustoconically shaped section reduces indiameter in a direction from a first end of the injector structure to anoutlet end so that the smaller diameter end of the frustoconical shapelies at the axial coordinate of the contact location along the injectoraxis, or at least faces downstream of the flow paths in the injectorstructure. Where the heating medium flow path includes an annular,frustoconically shaped section adjacent to the contact location, theproduct flow path may likewise include a frustoconically shaped sectionadjacent to the contact location, similarly reducing in diameter in thedirection from the first end of the injector structure to the outletend.

A heating medium injector according to the first aspect of the inventionmay also include a mixture flow path formed within the injectorstructure between the contact location along the injector axis and theoutlet end of the injector structure. The mixture flow path is definedat least by a mixture flow path outer surface. According to someimplementations of the present invention, the mixture flow path outersurface is in substantial thermal communication with at least onemixture flow path outer surface cooling structure. In someimplementations, the mixture flow path is also defined by an innersurface at least in a region adjacent to the contact location, that is,immediately downstream from the contact location in the direction offlow. This mixture flow path inner surface may by defined by acone-shaped element positioned coaxially with the heating medium annularflow path and decreasing in diameter in a direction from the first endto the outlet end of the injector structure.

The cooling structure along the second flow surface of the product flowpath may extend past the contact location to at least a portion of themixture flow path outer surface. Thus the same cooling structure may beused in methods according to the invention to cool both the second flowsurface of the product path (a surface upstream of the contactlocation), and at least a portion of the mixture flow path outer surface(a surface downstream of the contact location).

Injectors and injection methods according to the present invention maybe used with any heating medium suitable for the desired heat treatment.A heating medium comprising steam is particularly advantageous for heattreatments in which the product is to be returned to a lower temperatureafter a short time at a pasteurization temperature because watercondensed in the heating process may be vaporized to rapidly reduce thetemperature of the product from the pasteurization temperature. However,the present invention is by no means limited to use with steam as theheating medium. Also, the invention is not limited to any particularpurpose of the heat treatment. Although injectors and injection methodsaccording to the present invention have particular application topasteurizing foodstuffs, especially foodstuffs including raw meat or eggproteins as described above, the invention is not limited to thisapplication. Other applications for injectors and injection methodsaccording to the present invention include cooking foodstuffs,sterilizing foodstuffs which have already been cooked, or simultaneouslycooking and sterilizing foodstuffs for example.

Other aspects of the present invention include products produced by themethods described herein. These products include in particular productscontaining raw meat or egg protein produced by any of the methodsdescribed herein.

These and other advantages and features of the invention will beapparent from the following description of representative embodiments,considered along with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is longitudinal section view of a heating medium injectorembodying the principles of the invention having a first flow pathconfiguration.

FIG. 2 is a section view taken along line 2-2 in FIG. 1.

FIG. 3 is a longitudinal section view of an alternate heating mediuminjector embodying the principles of the invention having the first flowpath configuration.

FIG. 4 is a longitudinal section view of another alternate heatingmedium injector having the first flow path configuration.

FIG. 5 is longitudinal section view of a heating medium injectorembodying the principles of the invention having a second flow pathconfiguration.

FIG. 6 is a section view taken along line 6-6 in FIG. 5.

FIG. 7 is a longitudinal section view of an alternate heating mediuminjector having the second flow path configuration.

FIG. 8 is a longitudinal section view of another alternate heatingmedium injector embodying the principles of the invention having thesecond flow path configuration.

FIG. 9 is a schematic representation of a heating medium injectionsystem including a heating medium injector in accordance with thepresent invention.

DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

In the following description of representative embodiments FIGS. 1-4will be used to describe three different embodiments having the samegeneral flow path configuration. FIGS. 5-8 will be used to describethree different embodiments having an alternate flow path configuration.It should be appreciated however, that the invention is by no meanslimited to the two general flow path configurations used in theexamples.

Referring to FIG. 1, a heating medium injector 100 embodying principlesaccording to the present invention includes an injector structure madeup of a center component 101, a first end component 102, an intermediatecomponent 103, and a second end component 104. In the orientation ofFIG. 1 a left end of injector 100 represents an inlet end indicatedgenerally at 106 while the right end of the injector in FIG. 1represents an outlet end indicated generally at 107. The combinedcomponents 101, 102, 103, and 104 are connected together along aninjector axis shown in the drawing as A1.

First end component 102 is connected in example injector 100 to secondend component 104 through a flange 110 and connecting bolts 111. Thisflange connecting arrangement also captures intermediate component 103between first end component 102 and second end component 104 with anintermediate component flange 112 abutting first end component flange110. Center component 101 is received through an opening 114 in firstend component 102 and extends along injector axis A1 through a passage118 defined by first end component 102 and intermediate component 103.Connecting screws 115 connect center component 101 in place on first endcomponent 102 and seals 116 provide a liquid-tight seal between theexterior of center component 101 and opening 114.

Together, the various components define two separate flow paths throughinjector 100 to a contact location CL1. In this case contact locationCL1 comprises an annular area defined along plane C1 extendingperpendicular to injector axis A1. Contact location CL1 defines thecoordinate along injector axis A1 where the two flow paths, that is, theproduct flow path and heating medium flow path, come together in theinjector so that the materials flowing along those flow paths to theright in the orientation of the figure come together and may mix. One ofthese flow paths is shown in the figure at 120 while the other flow pathis shown at 121. Arrows 120A indicate the direction of flow along flowpath 120 and arrows 121A indicate the direct of flow along flow path121. Injector 100 also defines an outlet or mixture flow path shown at122, which in this example structure is defined in outlet end component104 to the right of line C1. In this example injector 100, flow path 120extends from an inlet opening 124 of first end component 102 through anarcuate section or “elbow” formed in the first end component and throughan axial section of passage 118 that runs from the right-most part offirst end component 102 through intermediate component 103 to thecontact location CL1. Flow path 121 through injector 100 is defined bytwo inlet passages 126 formed within second end component 104 and acentral chamber 127 which leads to mixture flow path 122 defined in partby an outlet passage 128 extending to an injector outlet opening 129.

It will be appreciated from FIG. 1 and the transverse section view ofFIG. 2 that flow path 120 in the region to the right of the arcuateportion of the path comprises an annular flow path defined between afirst surface 132 and second surface 133. In this example configuration,first surface 132 in the region just to the left of the contact locationCL1 is defined by the inner surface of intermediate component 103.Second surface 133 is defined in this region by the exterior surface ofcenter component 101. It should also be noted that in the configurationof FIG. 1, the flow path 121 also comprises an annular flow path definedon the inside by surface 134 and on the outside by surface 135. Surface134 comprises an outer surface of intermediate component 103 and surface135 comprises an inside surface of chamber 127 defined within secondcomponent 104.

Center component 101 and intermediate component 103 in FIG. 1 are formedfrom a material such as stainless steel which is not a TMOD material asdefined for purposes of this disclosure and the following claims, whilesecond end component 104 is formed from a TMOD material. Thus exampleinjector 100 incorporates both cooling structures and TMOD material toreduce or eliminate product constituent deposition on surfaces withinthe injector. In particular, a center component cooling structure in theexample of FIG. 1 comprises a coolant circulating chamber 140 at the tipof center component 101 which extends to the right in the figure pastthe coordinate of contact location CL1 along axis A1. This centercomponent coolant circulating chamber 140 is connected to receive acoolant fluid through a coolant inlet passage 141 and return coolantfluid through a coolant outlet passage 142. Injector 100 also includes acooling structure associated with intermediate component 103, namely, acoolant circulating chamber 144 extending through the intermediatecomponent body adjacent to surface 132. This coolant circulating chamber144 in intermediate component 103 is connected to a coolant inletpassage 145 and a coolant outlet passage 146 to facilitate circulatingcoolant fluid through the chamber. It should be noted that coolantcirculating chambers 140 and 144, and other coolant circulating chambersdisclosed herein may include baffles, dams, dividers, and other flowdirecting features positioned appropriately to direct the flow ofcoolant fluid throughout the respective chamber to provide the desiredcooling across the entire adjacent surface to be cooled. These flowdirecting features are not shown in the drawings in order to avoidobscuring the invention in unnecessary detail. It will be appreciated bythose in the field that any suitable arrangement of flow directingfeatures may be used in a coolant circulating chamber in accordance withthe present invention. Turbulence inducing devices may also be includedin a coolant circulating chamber in accordance with the presentinvention to induce turbulence in the circulated coolant and therebyenhance the cooling effect of the coolant. It should also be noted thatthe relative size of the coolant circulating chambers 140 and 144 shownin FIG. 1 and particularly FIG. 2 are shown only for purposes of exampleand are not limiting. The relative size of the flow paths 120 and 121and coolant circulating chambers 140 and 144 may be selected as desiredor necessary to facilitate the desired flow rates, and, in the case ofchambers 140 and 144, facilitate the cooling necessary to reach thedesired operating temperature of the surface being cooled.

In addition to coolant circulating chambers 140 and 144, the embodimentof FIG. 1 also forms surfaces of flow path 121 and surfaces of mixtureflow path 122 from a TMOD material. In this case, the entire second endcomponent 104 is formed from a TMOD material. Thus the outer surface 135of mixture flow path 122 is formed in a TMOD material as is the surface148 of outlet flow passage 128.

In operation of the example injector 100 shown in FIG. 1, a product tobe treated may be pumped or otherwise caused to flow into the injectorthrough inlet opening 124 and along the flow path 120 in the directionindicated by arrows 120A toward the contact location CL1 along injectoraxis A1. Heating medium may be directed in through each inlet opening125 and into each passage 126 along the flow path 121 in the directionindicated by arrows 121A to the contact location CL1. The annular flowof product and annular flow of heating medium come together at thecontact location CL1 where the heating medium quickly heats the productto the desired treatment. The heated mixture comprising heated productand heating medium continue to flow through mixture path 122 in thedirection of arrow 122A and out through outlet passage 128 andultimately exits the injector through outlet opening 129 to a suitablehold tube (not shown in FIG. 1) where the product is held at the desiredtemperature for a desired time.

While the product to be treated is directed along the product flow path120 in the direction indicated by arrows 120A and heating medium isdirected along the heating medium flow path 121 in the directionindicated by arrows 121A, heat from the heating medium is picked up bythe material of wall 130 separating the heating medium flow path fromthe product flow path. Heat from the injected heating medium also heatsthe surfaces 117 at the rightmost end of center component 101, and thisheat may radiate through the material of the center component to otherparts of that component including surface 133 which defines a portion ofthe product flow path in the region to the left of contact location CL1.In order to at least reduce the rate at which constituents from theproduct form deposits on surfaces 117 and 133, the operation of injector100 also includes circulating a suitable coolant through the centercomponent cooling chamber 140. This circulation of coolant throughchamber 140 removes heat from surface 133 and 117 of center component103 to reduce the temperature of those surfaces to temperatures belowthose at which the product being treated tends to adhere to a surfaceand thus reduce the rate at which product constituents may tend toadhere to the surfaces. In the operation of injector 100, coolant isalso circulated through chamber 144 located in intermediate component103 to remove heat from surface 132 and thereby reduce the temperatureof that surface to the desired temperature and thus reduce the rate atwhich product constituents may tend to adhere to that surface.Meanwhile, product constituent deposition is inhibited at surfaces 135and 148 of the second end component because those surfaces are formed ina TMOD material. In particular, the specific heat of the TMOD materialor the specific heat of such material combined with the thermalconductivity of that material allow injector 100 to be operated whilemaintaining the temperature of the surfaces 135 and 148 below atemperature at which product may tend to adhere to those surfaces. Theresistance to temperature increase provided by the TMOD material or theresistance to temperature increase combined with the conduction of heataway from the material allows the surfaces 135 and 148 to remain belowthe desired operating temperatures for those surfaces even though thosesurfaces are exposed to the heated mixture stream at a highertemperature as will be discussed further below. Although theimplementation shown in FIG. 1 includes TMOD material at surfaces 135and 148, it will be appreciated that other implementations may includecooling structures at these locations instead of TMOD materials. FIG. 3discussed below comprises such an implementation. Cooling structures atthese locations may be required for commercial operation for some typesof products such as products including raw meat and egg proteins.

Surfaces 133 and 117 in FIG. 1 are in substantial thermal communicationwith the cooling structure comprising coolant circulating chamber 140 byvirtue of the thermal conductivity of the material from which the wallsdefining surfaces 133 and 117 are formed (preferably but not necessarilyover approximately 10 W/m K) combined with the thickness of the materialbetween chamber 140 and surfaces 133 and 117, which may be onlyapproximately 0.02 to approximately 0.05 inches for example. Substantialthermal communication may also be provided through a thicker wall ofmaterial. Similarly, surface 132 is in substantial thermal communicationwith the cooling structure comprising coolant circulating chamber 144 byvirtue of the thermal conductivity of the material from which wall 130is formed (again, preferably but not necessarily over approximately 10W/m K) combined with the thickness of the material between chamber 144and surface 132, which may also be approximately 0.02 to approximately0.05 inches for example, but may be thicker for structural or otherpurposes. Other arrangements providing substantial thermal conductivitybetween a respective coolant circulating chamber such as 140 and asurface such as 133 and 117 in the example of FIG. 1, may includemultiple layers of material residing between the coolant circulatingchamber and surface to be cooled wall. For example, the wall of materialbetween chamber 140 and surfaces 133 and 117 may be formed from a thinfirst layer of material having a first thermal conductivity, and asecond layer having the same or preferably higher thermal conductivity.

In arrangements such as that shown in FIG. 1 where cooling structuresare used to cool surface 133 opposite wall 130, the cooling structuresneed not, and preferably do not, extend along the entire length of thecomponent 101 as indicated in the simplified drawing. Rather, thecooling structure (in this case coolant circulating chamber 140) mayextend only along the length of surface 133 opposite wall 130. Thecoolant circulating passages 141 and 142 may extend along the component101 closer to axis A1 and insulating materials may be included incomponent 101 to help reduce any cooling of product along path 120 priorto surface 133 opposite wall 130 and chamber 127.

Where cooling structures are used to cool surfaces so as to reducedeposition rates according to aspects of the present invention, thetemperature to which the given surface is cooled may be a temperaturebelow temperatures at which product tends to adhere to a surface. Thistemperature will vary with the product being treated. For productsincluding raw meat or egg proteins, for example, surfaces which arecooled by a cooling structure may be cooled to a temperature preferablyno more than approximately 135° F., and more preferably no more thanapproximately 130° F. Some products may tend to adhere to surfaces athigher temperatures than this example, while still other products maytend to adhere to surfaces at lower temperatures. The cooling structuresin each case may be operated in accordance with the invention tomaintain the desired operating temperature to resist the deposition ofproduct constituents in operation of the injector according to thepresent invention. This operating temperature, however, need not bemonitored in the operation of an injector in accordance with theinvention and practice of a method in accordance with the invention.Rather, the cooling needed for a given application may be determinedempirically and the process controlled to provide that empiricallydetermined level of cooling to reduce the deposit of productconstituents within the injector. It will be noted that the product flowpath surfaces and heated mixture flow path surfaces formed in a TMODmaterial in accordance with the present invention may also be maintainedbelow temperatures at which product tends to adhere to the surface byvirtue of the properties of the TMOD material.

Operating parameters of a heating medium injector incorporating aspectsof the present invention will depend in some cases on the particularproduct which is being treated. In particular, the treatment temperaturewill depend in large part upon the product being treated and the goal ofthe heat treatment. Where the product includes raw meat or egg proteinswhich are to remain undenatured over the course of the treatment, thegoal of the treatment may be to destroy pathogens such as Escherichiacoli (E. coli) O157:H7, Salmonella, Listeria, and Campylobacterbacteria, and in this case the target treatment temperature for theproduct in the heated mixture stream may be between approximately 158°F. and approximately 185° F. and the hold time at that temperature untilrelease into the vacuum chamber may be less than one second. Of course,the present invention is by no means limited to this temperature rangeand hold time, which is provided merely as an example of operation.

It will be noted from the example described above for products includingraw meat or egg proteins that the treatment temperature of approximately158° F. to approximately 185° F. is well above the temperature of asurface at which the product tends to adhere to the surface, namely,approximately 135° F. for example. Thus without the surface cooling inaccordance with the present invention, surfaces within a direct heatingmedium injector would quickly reach and exceed the adherence temperatureand product deposits would quickly form. Cooling surfaces in accordancewith the present invention prevents the given surfaces from reaching theadherence temperatures and thus reduce or eliminate product depositionon those surfaces. In some applications, forming surfaces in a TMODmaterial may likewise prevent such surfaces from reaching the adherencetemperature and thus reduce or eliminate product deposition on thosesurfaces.

FIG. 3 shows an injector 300 having a structure similar to the structureof injector 100 in FIG. 1 and providing product, heating medium, andmixture flow paths (320, 321, and 322, respectively) similar to thoseshown in FIG. 1, but including a different arrangement of coolingstructures. Injector 300 includes a center component 301, first endcomponent 302, and intermediate component 303 identical to those shownin FIG. 1. However, injector 300 in FIG. 3 includes a second endcomponent 304 that is not formed from a TMOD material. For example,second end component 304 may be formed from a stainless steel alloysuitable for food processing applications. Second end component 304includes a cooling structure associated with an outlet passage 328 andportions of a central chamber 327 formed by the second end component. Inthis example the cooling structure includes a coolant circulatingchamber 360 which extends in close proximity to the wall forming centralchamber 327 and in close proximity to surface 348 of outlet passage 328.A coolant inlet passage 361 is connected to chamber 360 as is a coolantoutlet passage 362 for allowing coolant to be circulated through chamber360.

In the operation of injector 300 shown in FIG. 3, center componentcooling chamber 340 and intermediate component cooling chamber 344perform the same function as the corresponding chambers in injector 100.In particular, center component cooling chamber 340 cools the endsurfaces 317 of center component 301 along with surface 333 of theproduct flow path 320 in the direction shown by arrows 320A.Intermediate coolant chamber 344 cools surface 332 of the product flowpath 320. Coolant chamber 360 in the injector 300 cools surfaces 348 ofoutlet passage 328 and surfaces of chamber 327 particularly those pastthe contact location CL3 and plane C3 along axis A3 which may come incontact with product during the course of operation.

Injector 400 shown in FIG. 4 also has a structure similar to that shownfor injector 100 in FIG. 1. Namely, injector 400 includes a centercomponent 401, a first end component 402, an intermediate component 403,and a second end component 404. These components 401, 402, 403, and 404are identical in external shape to the corresponding components shown ininjector 100 and thus define the same configuration of product, heatingmedium, and mixture flow paths as those set out in FIG. 1 (labeled 420,421, and 422 in FIG. 4). However, in the example of injector 400, theentire center component 401, and the entire intermediate component 403are formed from a TMOD material. Second end component 404 is formed froma TMOD material similarly to second end component 104 shown in FIG. 1for injector 100. Rather than employing coolant circulating chamberssuch as center component coolant circulating chamber 140 in FIG. 1 andintermediate component coolant circulating chamber 144 in FIG. 1,injector 400 employs TMOD materials to inhibit the deposition of productconstituents on and surfaces 417, surfaces 433 and 432 of the productflow path, and surfaces 448 of outlet passage 428, and on surfaces ofcentral chamber 427 downstream of the contact location CL4 along axisA4. This application of TMOD materials may be effective for treatingsome types of products, although not products containing raw meat or eggproteins.

It should also be noted that an injector having the configuration shownin FIGS. 1, 3, and 4 may also be operated with the flow paths for theproduct and the heating medium switched from that described above. Inparticular, and referring back to FIG. 1 for example, heating medium maybe directed through the flow path 120 while product may be directedalong the flow path indicated by 121. In this mode of operation, thestructure may be changed so that no center component cooling structureis included or the center component cooling structure is effective forcooling only the surfaces 117 at the end of center component 101 anddoes not cool the surfaces of center component 101 along surface 133opposite wall 130. Also, in the case where product is introduced intoinjector 100 along the flow path 121, cooling structures will berequired along surfaces 135 and 148. Where intermediate componentcoolant circulating chamber 144 is required to cool surface 134 for aparticular product, that chamber may be located in closer proximity tosurface 134 than shown in FIG. 1 to provide more effective cooling tothat surface.

FIG. 5 shows another injector 500 according to the principles of theinvention with a somewhat different structure than injectors 100, 300,and 400. Injector 500 includes a center component 501, a first endcomponent 502, and a second and component 504. First end component 502includes a flange 510 that may be used together with suitable bolts (notshown) to connect to second end component 504. First end component 502also defines a center component receiving opening 514 for receiving anelongated portion of center component 501. Center component 501 may beconnected to first end component 502 through suitable bolts 515 andsealed using seals 516 similarly to manner in which center component 101is connected in injector 100 shown in FIG. 1. Unlike the structure shownin FIG. 1, first end component 502 includes a portion 512 whichprotrudes so as to extend into an axial passage defined by surface 511in second end component 504. Alternatively, this protruding portion 512may be a separately formed part connected between components 502 and504. When connected in the operating position shown in FIG. 5, opening514 extends along the injector axis A5 and through the protrudingportion 512 to the contact location CL5 at the intersection of line C5and the injector axis. Opening 514 is adapted to receive the elongatedportion of center component 501 but leaves a gap 513 between the outersurface of the center component and surface of opening 514. This gap 513defines a portion of a flow path through injector 500 which is indicatedin FIG. 5 at 521, with the remainder of the flow path defined by inletpassage 526 in first end component 502. The second flow path definedthrough injector 500 comprises flow path 520 which extends from an inletopening 524 in first end component 502, through an elbow section in thatcomponent, and into an annular area defined between surface 532 ofprotruding part 512 and surfaces 511 of second end component 504. Thisannular flow path extends to an outlet passage 528 which comprises amixture flow path leading to outlet opening 529 and defines outletpassage surfaces 548 in second end component 504. The annular shape ofthe flow path defined between surfaces 511 and 532 (comprising a portionof flow the flow path 520 in FIG. 5) is apparent especially from thetransverse section view of FIG. 6. FIG. 6 additionally shows that theflow path defined by surfaces of opening 514 and the exterior of centercomponent 501 (the flow path shown rows 521 in FIG. 5) also defines anannular flow path.

In the example of injector 500, the entire first end component 502 isformed from a TMOD material as is the entire center component 501.Second end component 504 is formed from a suitable food processing gradematerial which is not a TMOD material in this example structure such asa suitable stainless steel. In accordance with aspects of the presentinvention, a cooling structure is included in second end component 504.In the example of injector 500, this cooling structure comprises twoseparate coolant circulating chambers 560A and 560B which each extendover a different part of the axial opening defined by surfaces 511 andof the outlet passage 528, and each include a respective coolant inlet561A, 561B and coolant outlet 562A and 562B. Surprisingly,implementations of an injector having a configuration similar to thatshown in FIG. 5 in which the protruding part 512 is formed fromstainless steel (that is, not a TMOD material) allow treatment ofproducts containing raw meat proteins to temperatures of betweenapproximately 158° F. and approximately 185° F. without significantproduct constituent deposition on surfaces corresponding to surfaces 532in FIG. 5.

In a preferred manner of operating injector 500, heating medium isinjected through inlet 526 in first end component 502 and directed alongthe flow path 521 in the direction indicated by arrows 521A in FIG. 5,which comprises an annular flow path between surfaces of opening 514 andthe elongated part of 501 (gap 513). Also in this preferred mode ofoperation, product to be treated is directed into the injector throughinlet opening 524 and along the flow path 520 in the direction indicatedby arrows 520A including through the arcuate section and into theannular flow area defined between surfaces 511 and 532. The heatingmedium and product come together at the contact location CL5 and themixture then flows to the right in the orientation of FIG. 5 throughoutlet passage 528 and ultimately out of the injector through outletopening 529. As heating medium and product are so directed throughinjector 500, a suitable coolant is circulated through coolant chambers560A and 560B which together envelope the wall of material defining theentire surface 511. This circulation of coolant cools surface 511 to thedesired temperature or desired operational effectiveness for reducingproduct deposits for the given product and thereby inhibits thedeposition of constituents from the product on those surfaces inaccordance with the present invention. The TMOD material in whichsurface 532 is formed at the inside diameter of the annular product flowpath 520 inhibits the deposition of product constituents on thatsurface. Additionally, the TMOD material in which surfaces 517 areformed downstream from contact location CL5 along injector axis A5inhibits the deposition of product on those surfaces. It is noted thatin this injector configuration according to the present invention, thecoolant circulating chambers 560A and 560B each extend along a portionof the product flow path 520, and then traverse the line C5 and thusalso extend along the mixture flow path defined by passage 528. Thus thesame cooling arrangement provides the desired cooling and depositioninhibiting both upstream and downstream from contact location CL5 alonginjector axis A5.

An injector having the product and heating medium flow path arrangementshown in FIG. 5, may include a variation in which the material formingsurface 532 is not formed from a TMOD material and is not cooled inoperation. In this variation, the material forming surface 532 alongsome or all of the length of the surface may be formed from stainlesssteel. This variation relies on cooling only along surface 511 to reduceproduct constituent deposition along surface 511 and 532. Othervariations on injector 500 may include forming component 501 ofstainless steel or other materials which are not represent TMODmaterials.

The injector 700 shown in FIG. 7 comprises a structure similar to thatshown for injector 500 in FIG. 5. In particular, injector 700 includes acenter component 701, a first end component 702, and a second endcomponent 704. Injector 700 also includes a flow path 720 through whichproduct may be directed in the direction indicated by arrows 720A, and aflow path 721 through which heating medium may be directed in thedirection indicated by arrows 721A. Injector 700 differs from injector500 in that second end component 704 comprises a TMOD material. Thus nocooling structure is located along surfaces 711 and 748 formed in secondend component 704. Although injector 700 may be effective for reducingthe rate of product deposition for some products, the arrangementrelying entirely on TMOD materials is not suitable for use in treatingproducts containing raw meat proteins or raw egg proteins.

Injector 800 shown in FIG. 8 has a configuration of components similarto injector 500 shown in FIG. 1, including a center component 801, afirst end component 802, and a second end component 804. Second endcomponent 804 in injector 800 is similar to the corresponding component504 in FIG. 5 in that it is not formed from a TMOD material, but from asuitable material such as stainless steel. Thus second end component 804includes a cooling structure comprising coolant circulating chambers860A and 860B for cooling surface 811 and surface 848. Unlike thecorresponding components in injector 500 shown FIG. 5, center component801 and first end component 802 in injector 800 are also formed from amaterial such as a suitable stainless steel that is not a TMOD material.In view of the material from which these components 801 and 802 areformed, each also includes a cooling structure for cooling the desiredsurfaces. In particular center component 801 includes a coolingstructure comprising a coolant circulating chamber 840 at the right-handend of the center component in the orientation of the figure. Coolantcirculating chamber 840 is connected to a coolant inlet 841 and acoolant outlet 842 to facilitate circulation of the coolant material.First end component 802 includes a cooling structure comprising arespective coolant circulating chamber 836 adjacent to all of thesurfaces forming the flow path 820. This chamber 836 is associated witha coolant inlet 837 and coolant outlet 838 to facilitate circulating thedesired coolant material.

In operation of injector 800 shown in FIG. 8, product is directed alongthe flow path 820 in the direction indicated by arrows 820A, heatingmedium is directed along the flow path 821 in the direction indicated byarrows 821A, and the mixture is directed along the mixture flow path 822in the direction indicated by arrow 822A. A suitable coolant issimultaneously circulated through each of the chambers 840, 836, 860A,and 860B to cool the surfaces adjacent to the respective chambers andthereby inhibit the deposition of constituents from the product on theadjacent flow path surfaces.

As with the injector structure shown in FIGS. 1, 3, and 4, the injectorstructure shown in FIGS. 5, 7, and 8 may be operated with the flow pathsfor the heating medium and product switched. That is, in injector 500for example, product may be directed along the flow path 521 in thedirection indicated by arrows 521A and heating medium may be directedalong flow path 520 in the direction indicated by arrows 520A. In thismanner of operation, it is necessary to include cooling structures tocool the surfaces of component 501 along at least a portion of theproduct flow path 521 which overlaps with the flow path 520. In the caseof injector 700, no modifications of the structure are necessary inorder to direct heating medium along the flow path 720 in the directionindicated by arrows 720A and direct product along flow path 721 in thedirection indicated by arrows 721A, although it should be noted againthat this arrangement would not be suitable for some products,particularly, products containing raw meat proteins or containing rawegg proteins.

It will be appreciated that in order to direct product and heatingmedium into injector 100 and to facilitate the flow of mixed product andheating medium from the injector, suitable connecting structures such asflanges, compression fittings, or other connectors will be provided atthe various inlet openings such as openings 124 and 125 in FIG. 1, andeach outlet opening such as outlet opening 129 in FIG. 1. Suitableconnecting fittings or devices are also necessary for the coolantcirculating openings such as coolant inlets 561A and 561B and coolantoutlets 562A and 562B in FIG. 5. Since any number of different types ofconnecting structures may be used, and since such connecting structuresare well known in the art, these connecting structures are omitted fromthe drawings so as not to obscure the invention in unnecessary detail.

In the injector configuration shown in FIGS. 1, 3, and 4 and theconfiguration shown in FIGS. 5, 7, and 8, the respective centercomponent (101 in FIGS. 1 and 501 in FIG. 5 for example), is adjustablealong the respective injector axis (A1 in FIG. 1 and A5 in FIG. 5 forexample). Referring to FIG. 5 for example, center component 501 is inits right-most position in the orientation of the figure. Appropriatespacers between component 501 and component 502 at the left end ofcomponent 501 in the figure can be used to adjust the position ofcomponent 501 to the left so that plane C5 intersects the cone-shapedsurface 517. This has the effect of increasing the area of the annulusdefining the contact location CL5. A similar adjustment may be made inthe configuration shown in FIGS. 1, 3, and 4. Other implementations mayinclude adjusting mechanisms for the center component which do not relyon spacers and which facilitate adjustments of the center componentposition and contact location area during operation of the injector.

The schematic diagram of FIG. 9 shows a portion of a direct heatingmedium injection treatment system 900 in which an injector according tovarious aspects of the present invention may be used. In the illustratedsystem, heating medium injector 901 is connected to receive product tobe treated from a product supply 904 through a product supply line 905.Heating medium injector 901 is also connected to receive heating mediumfrom heating medium supply 908 through a heating medium supply line 909.A mixture flow path is shown at 910 in FIG. 9, and is shown connected toa hold tube structure 912. A hold tube structure suitable for use ashold tube structure 912 is disclosed in U.S. Provisional PatentApplication No. 62/808,778 filed Feb. 21, 2019, and entitled “DirectHeating Medium Injector and Injection System and Method,” the entirecontent of which is incorporated herein.

The illustrated injector 901 utilizes a cooling structure or coolingstructures to cool surfaces of the product flow path and mixture flowpath in the injector. These cooling structures are represented in FIG. 9as lines 914 extending along portions of the product flow path 916 andalong portions of mixture flow path 910, and in this example comprisecoolant circulating chambers through which a suitable coolant fluid maybe circulated to provide the desired cooling. Coolant fluid is directedthrough the cooling structures 914 from a coolant supply 920 connectedto the cooling structures by a coolant inlet line 921 and a coolantreturn line 922.

In operation of the system shown in FIG. 9, product is directed fromproduct supply 904 through the product flow path 916 in injector 901simultaneously as heating medium is directed through the injector atrates and in a proportion to achieve the desired temperature of theproduct in the hold tube structure 912 for the desired treatment time.As the product and heating medium are so directed, coolant fluid isdirected through the coolant circulating chambers 914 at a temperatureand rate to provide the desired cooling at the product and mixture flowpath surfaces on injector 901.

Although FIG. 9 shows a coolant structure arrangement for coolingcertain surfaces of the product flow path 916 and mixture flow path, itwill be appreciated from the previous discussion that implementations ofthe present invention are not limited to this arrangement. Rather,cooling structures such as coolant circulating chambers may be includedonly for portions of the product flow path and portions of the mixtureflow path, or a single coolant circulating chamber may be included forsome portion of the product flow path and/or mixture flow path. In theseimplementations a coolant supply such as 920 in FIG. 9 may be usedtogether with suitable connecting conduits to circulate the coolantfluid. In other implementations multiple coolant supplies may be used tosupply coolant fluid to the different coolant circulating chambers.

The invention encompasses numerous variations on the above-describedexample systems. Such variations include variations related to thecooling structures described in the above examples. Generally, where acooling structure is employed to remove heat from a surface forming partof a mixture flow path, the cooling structure may include any number ofsegments or elements to accomplish the desired cooling. For example, anynumber of separate or connected coolant circulating chambers may beincluded for a given surface. Also, although the illustrated examplesassume a certain direction of circulation through the coolantcirculation chambers, the direction of circulation may be reversed fromthat described. Furthermore, the invention is not limited to coolingstructures comprising coolant circulating chambers to provide thedesired cooling. Thermoelectric devices may also be used to provide thedesired cooling of a given surface according to the present invention,as may forced air cooling arrangements in which air is forced over finsor other heat conductive arrangements in substantial thermalcommunication with the surface to be cooled. A cooling structure withinthe scope of the invention may also employ evaporative cooling to removeheat from the desired flow path surfaces. Also, different types ofcooling structures may be used for different areas of a given surface tobe cooled.

For a given portion of a product flow path or mixture flow path, acooling structure may be immediately adjacent to the surface to becooled. However, cooling structures such as coolant circulating chambersmay not be continuous, but may include dividers, baffles, turbulenceinducing features, and other structures which prevent the coolantcirculating chamber from being continuous along a given surface. Sucharrangements in which the coolant circulating chamber may not becontinuous over a given surface to be cooled remain within the scope ofthe present invention as set out in the claims.

Surfaces which come in contact with the product and the mixture ofheated product and heating medium should have at least a suitable finishappropriate for the given product being treated in accordance with food(or other material) handling standards. Generally, the surface roughnessof any surface forming a portion of the mixture flow path should have avalue of 32 RA microinches or less. Lower surface roughness values mayenhance the deposition inhibiting performance of a cooled surface orsurface formed in a TMOD material in accordance with the invention.

As noted above, a TMOD material comprises a material having a specificheat of no less than approximately 750 J/kg K, and preferably no lessthan approximately 900 J/kg K, and, more preferably, no less thanapproximately 1000 J/kg K. Of course, where the product being treated isa foodstuff or pharmaceutical, a TMOD material must also be suitable forproviding food contact surfaces. A class of materials particularlysuited for use as a TMOD material in accordance with the presentinvention comprises plastics which have a specific heat of no less thanapproximately 1000 J/kg K and are suitable for providing food contactsurfaces, retain structural integrity, maintain dimensional stability,and do not degrade at temperatures which may be encountered in a steaminjection system. These plastics include polyetheretherketone (PEEK),Nylon, Ultra-high-molecular-weight polyethylene (UHMWPE),polytetrafluoroethylene (Teflon), polyoxymethylene (POM or Acetal), andpoly methyl methacrylate (acrylic), for example. These plastics suitablefor use as TMOD material in accordance with the present invention mayinclude various additives and may be used in both an unfilledcomposition or a filled (composite) composition, such as glass-filled orcarbon-filled, provided the filled material remains suitable for foodcontact, retains the desired specific heat as described above in thisparagraph and is capable of providing the desired surface finish.Materials other than plastics may also be employed for TMOD materialwithin the scope of the present invention. These materials includeceramics such as porcelain, glasses such as borosilicate glass (Pyrex),and rubber. These materials also include aluminum which has a specificheat of approximately 900 J/kg K and a thermal conductivity ofapproximately 240 W/m K, as well as magnesium and beryllium and alloysof these materials and Albemet. Materials having a specific heat ofsomewhat less than approximately 750 J/kg K but exhibit relatively highthermal conductivity may also represent a suitable substitute for a TMODmaterial. Such materials may have a specific heat of no less thanapproximately 650 J/kg K and a thermal conductivity of no less thanapproximately 100 W/m K and include silicon carbide for example. Also, aTMOD material within the scope of the present invention may comprise amixture of materials and need not comprise a single material. Forexample, a TMOD material may comprise a mixture of different types ofthermoplastics, or plastics and other materials such as quartz and epoxyresin composite materials for example, or may be made up of layers ofmetals, plastics, and other materials and combinations of such materialsin different layers. A TMOD material also need not be continuous along agiven surface. For example, a give surface formed in a TMOD materialaccording to the present invention may be formed in PEEK over a portionof its length and may be formed in a different plastic or other TMODmaterial over another portion of its length.

It should also be noted that although the example TMOD components shownin the drawings indicate that the entire component is formed from TMODmaterial, embodiments of the present invention are not limited tocomponents formed entirely of TMOD material. In some implementations forexample, a component defining a portion of the product path surfaces orof the mixture path surfaces may comprise an inner sleeve in which theflow path surface is formed. This inner sleeve may be mounted in orconnected to an outer housing that is not formed from a TMOD material,but provided for some purpose unrelated to the TMOD function such as tofacilitate assembly of the system or to provide structural support.

It is also possible in accordance with the present invention to utilizecooling structures together with TMOD materials. Although not limited tosuch materials, this use of cooling structures is particularlyapplicable to TMOD materials such as aluminum having high thermalconductivity. In any event, the limitations as set out in the followingclaims that a given surface is in substantial thermal communication witha cooling structure is not intended to exclude the combination of thosetwo features. A given surface may be both formed in a TMOD material andbe in substantial thermal communication with a cooling structureaccording to the following claims.

As used herein, whether in the above description or the followingclaims, the terms “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” and the like are to be understood to beopen-ended, that is, to mean including but not limited to. Also, itshould be understood that the terms “about,” “substantially,” and liketerms used herein when referring to a dimension or characteristic of acomponent indicate that the described dimension/characteristic is not astrict boundary or parameter and does not exclude variations therefromthat are functionally similar. At a minimum, such references thatinclude a numerical parameter would include variations that, usingmathematical and industrial principles accepted in the art (e.g.,rounding, measurement or other systematic errors, manufacturingtolerances, etc.), would not vary the least significant digit.

Any use of ordinal terms such as “first,” “second,” “third,” etc., inthe following claims to modify a claim element does not by itselfconnote any priority, precedence, or order of one claim element overanother, or the temporal order in which acts of a method are performed.Rather, unless specifically stated otherwise, such ordinal terms areused merely as labels to distinguish one claim element having a certainname from another element having a same name (but for use of the ordinalterm).

In the above descriptions and the following claims, terms such as top,bottom, upper, lower, and the like with reference to a given feature areintended only to identify a given feature and distinguish that featurefrom other features. Unless specifically stated otherwise, such termsare not intended to convey any spatial or temporal relationship for thefeature relative to any other feature.

The term “each” may be used in the following claims for convenience indescribing characteristics or features of multiple elements, and anysuch use of the term “each” is in the inclusive sense unlessspecifically stated otherwise. For example, if a claim defines two ormore elements as “each” having a characteristic or feature, the use ofthe term “each” is not intended to exclude from the claim scope asituation having a third one of the elements which does not have thedefined characteristic or feature.

The above described preferred embodiments are intended to illustrate theprinciples of the invention, but not to limit the scope of theinvention. Various other embodiments and modifications to thesepreferred embodiments may be made by those skilled in the art withoutdeparting from the scope of the present invention. For example, in someinstances, one or more features disclosed in connection with oneembodiment can be used alone or in combination with one or more featuresof one or more other embodiments. More generally, the various featuresdescribed herein may be used in any working combination.

The invention claimed is:
 1. A heating medium injector including: (a) aninjector structure extending along an injector axis from a first end toan outlet end; (b) a heating medium flow path defined within theinjector structure, the heating medium flow path extending from aheating medium inlet opening to a contact location; (c) a product flowpath defined within the injector structure, the product flow pathextending from a product inlet opening to the contact location, theproduct flow path in a first region being defined between a first flowsurface and a second flow surface, the first flow surface comprising asurface of a first boundary wall separating the heating medium flow pathfrom the product flow path in the first region and the second flowsurface comprising a surface of a second boundary wall; (d) the contactlocation comprising a location within the injector structure at whichthe heating medium flow path and product flow path first merge in adirection from the first end of the injector structure to the outlet endof the injector structure; and (e) at least some of the second flowsurface of the product flow path is in substantial thermal communicationwith a second flow surface cooling structure formed within or connectedto the second boundary wall and isolated from the product flow path. 2.The heating medium injector of claim 1 wherein the second flow surfacecooling structure comprises a coolant circulating chamber connected to acoolant inlet at an exterior of the injector structure and to a coolantoutlet at the exterior of the injector structure.
 3. The heating mediuminjector of claim 1: (a) further including a mixture flow path formedwithin the injector structure between the contact location along theinjector axis and the outlet end of the injector structure; (b) whereina first region of the mixture flow path adjacent to the contact locationis defined at least in part by a mixture flow path outer surface; and(c) wherein the mixture flow path outer surface is in substantialthermal communication with a mixture flow path outer surface coolingstructure which is isolated from the mixture flow path.
 4. The heatingmedium injector of claim 3 wherein the mixture flow path outer surfacecooling structure comprises a coolant circulating chamber connected to acoolant inlet at an exterior of the injector structure and to a coolantoutlet at the exterior of the injector structure.
 5. The heating mediuminjector of claim 1: (a) further including a mixture flow path formedwithin the injector structure between the contact location along theinjector axis and the outlet end of the injector structure; (b) whereinthe mixture flow path is defined at least in part by a mixture flow pathouter surface; and (c) wherein the second flow surface cooling structuretraverses a plane of the contact location so as to extend along at leasta portion of the second flow surface of the product flow path and atleast a portion of the mixture flow path outer surface, and wherein thesecond flow surface cooling structure is also isolated from the mixtureflow path.
 6. The heating medium injector of claim 5 wherein the secondflow surface cooling structure comprises a coolant circulating chamberconnected to a coolant inlet at an exterior of the injector structureand to a coolant outlet at the exterior of the injector structure. 7.The heating medium injector of claim 1 wherein: (a) the heating mediumflow path in the first region comprises a heating medium annular flowpath; and (b) the product flow path in the first region comprises aproduct annular flow path that is coaxial with the heating mediumannular flow path such that the first boundary wall comprises an annularwall between the heating medium annular flow path and the productannular flow path.
 8. The heating medium injector of claim 7: (a)further including a mixture flow path formed within the injectorstructure between the contact location along the injector axis and theoutlet end of the injector structure; (b) wherein a first region of themixture flow path adjacent to the contact location is defined between amixture flow path outer surface and a mixture flow path inner surface,the mixture flow path inner surface being defined by a cone-shapedelement positioned coaxially with the heating medium annular flow pathand decreasing in diameter in the direction from the first end of theinjector structure to the outlet end of the injector structure; and (c)wherein the mixture flow path outer surface is in substantial thermalcommunication with a mixture flow path outer surface cooling structurewhich is isolated from the mixture flow path.
 9. The heating mediuminjector of claim 8 wherein the product flow path includes afrustoconically shaped section adjacent to the contact location andreduces in diameter in the direction from the first end of the injectorstructure to the outlet end of the injector structure.
 10. The heatingmedium injector of claim 9 wherein: (a) the second flow surface coolingstructure comprises a second flow surface coolant circulating chamber;and (b) the mixture flow path outer surface cooling structure comprisesa mixture flow path outer surface coolant circulating chamber.
 11. Theheating medium injector of claim 10 wherein the second flow surfacecoolant circulating chamber is in fluid communication with the mixtureflow path outer surface coolant circulating chamber.
 12. A method forinjecting a heating medium into a product, the method including: (a)directing the heating medium in a heating medium flow path from aheating medium inlet to a contact location spaced apart from the heatingmedium inlet along an injector axis; (b) directing a product to betreated in a product flow path from a product inlet to the contactlocation which is spaced apart from the product inlet along the injectoraxis, the product flow path in a first region along the injector axisbeing defined between a first flow surface and a second flow surface,the first flow surface comprising a surface of a first boundary wallseparating the heating medium flow path from the product flow path andthe second flow surface comprising a surface of a second boundary wall;and (c) while directing the heating medium in the heating medium flowpath and directing the product in the product flow path, cooling atleast some of the second flow surface through a second flow surfacecooling structure isolated from the product flow path.
 13. The method ofclaim 12 wherein the second flow surface cooling structure includes asecond flow surface coolant circulating chamber located adjacent tosecond flow surface and cooling the at least some of the second flowsurface includes circulating a second flow surface coolant fluid throughthe second flow surface coolant circulating chamber.
 14. The method ofclaim 12: (a) further including directing a mixture of the heatingmedium and the product to be treated through a mixture flow pathextending between the contact location and an injector outlet; (b)wherein a first region of the mixture flow path adjacent to the contactlocation is defined at least in part by a mixture flow path outersurface; and (c) cooling the mixture flow path outer surface through amixture flow path cooling structure located adjacent to the mixture flowpath outer surface and isolated from the mixture flow path.
 15. Themethod of claim 12: (a) further including directing a mixture of theheating medium and the product to be treated through a mixture flow pathextending between the contact location and an injector outlet; (b)wherein a first region of the mixture flow path adjacent to the contactlocation is defined at least in part by a mixture flow path outersurface; (c) wherein the second flow surface cooling structure includesa contact location coolant circulating chamber adjacent to at least someof the second flow surface and to at least some of the mixture flow pathouter surface and cooling the at least some of the second flow surfaceincludes circulating a coolant fluid through the contact locationcoolant circulating chamber; and (d) cooling the mixture flow path outersurface includes circulating the coolant fluid through the contactlocation coolant circulating chamber.
 16. The method of claim 12wherein: (a) directing the heating medium in the heating medium flowpath includes directing the heating medium in a heating medium annularflow path in the first region; and (b) directing the product in theproduct flow path includes directing the product in a product annularflow path that is coaxial with the heating medium annular flow path suchthat the first boundary wall comprises an annular wall between theheating medium annular flow path and the product annular flow path. 17.The method of claim 16: (a) further including directing a mixture of theheating medium and the product to be treated through a mixture flow pathextending between the contact location and an injector outlet opening;(b) wherein a first region of the mixture flow path adjacent to thecontact location is defined between a mixture flow path outer surfaceand a mixture flow path inner surface, the mixture flow path innersurface being defined by a cone-shaped element positioned coaxially withthe heating medium annular flow path and decreasing in diameter in adirection from the contact location to the injector outlet opening; (c)wherein the mixture flow path outer surface is in substantial thermalcommunication with a mixture flow path outer surface cooling structureextending along the mixture flow path and isolated from the mixture flowpath; and (d) cooling at least some of the mixture flow path outersurface via the mixture flow path outer surface cooling structure. 18.The method of claim 17 wherein the second flow surface cooling structureincludes a second flow surface coolant circulating chamber and coolingthe at least some of the second flow surface includes circulating asecond flow surface coolant fluid through the second flow surfacecoolant circulating chamber.
 19. The method of claim 18 wherein themixture flow path outer surface cooling structure includes a mixtureflow path outer surface coolant circulating chamber and cooling the atleast some of the mixture flow path outer surface includes circulating acoolant fluid through the mixture flow path outer surface coolantcirculating chamber.